1. Field of the Invention
The present invention relates generally to radiation therapy devices, and more particularly, to the automated delivery and monitoring of radiation therapy.
2. Description of the Related Art
Conventional radiation therapy typically involves directing a radiation beam at a tumor in a patient to deliver a predetermined dose of therapeutic radiation to the tumor according to an established treatment plan. This is typically accomplished using a radiation therapy device such as the device described in U.S. Pat. No. 5,668,847 issued Sep. 16, 1997 to Hernandez, the contents of which are incorporated herein for all purposes.
The radiotherapy treatment of tumors involves three-dimensional treatment volumes which typically include segments of normal, healthy tissue and organs. Healthy tissue and organs are often in the treatment path of the radiation beam. This complicates treatment, because the healthy tissue and organs must be taken into account when delivering a dose of radiation to the tumor. While there is a need to minimize damage to healthy tissue and organs, there is an equally important need to ensure that the tumor receives an adequately high dose of radiation. Cure rates for many tumors are a sensitive function of the dose they receive. Therefore, it is important to closely match the radiation beam""s shape and effects with the shape and volume of the tumor being treated. It is also important to properly position the patient on the treatment table to avoid damaging tissue and critical organs.
Portal imaging techniques have been developed to assist in positioning patients, and in verifying the shape of a field delivered to a treatment area on the patient. Most portal imaging techniques utilize photographic films which are carefully positioned by an operator by hand. Because most radiation therapy devices are located within vaults constructed with thick concrete walls and thick doors which can take 30 seconds to open and close, it can take a significant amount of time for an operator to position the film, leave the room, operate the radiation therapy device to deliver radiation, and enter the room to remove the film with the captured portal image.
Electronic portal imaging techniques have also been used which avoid the need to switch films to take multiple images and which eliminates the need to process and expose films to view a portal image. Such electronic techniques, however, still require manual intervention by an operator to configure and manipulate the portal imager, by entering the treatment room. It would be desirable to provide a portal imaging approach which reduces or eliminates the amount of manual intervention required. It would further be desirable to provide a portal imaging approach which integrates control of the portal imager with operation of the radiation therapy device.
According to one embodiment of the present invention, a system, method, apparatus, and means for controlling a portal imager includes operating a radiation therapy device to identify segment data defining a radiation therapy segment, identifying (from the segment data) portal position information, and positioning a portal imaging device based on the portal position information. The radiation therapy device may be further operated to identify field information identifying a radiation field to be delivered, position elements of the radiation therapy device to deliver the field, deliver the field, and capture a portal image on the portal imaging device.
In some embodiments, the portal imaging device is a flat panel detector movably coupled to a gantry of the radiation therapy device. In some embodiments, the portal imaging device is positioned using a drive motor controlled by control signals received from an operators console. In some embodiments, the portal imaging device may be positioned a number of times during a treatment based on position information for each segment of the treatment.
The present invention is not limited to the disclosed preferred embodiments, however, as those skilled in the art can readily adapt the teachings of the present invention to create other embodiments and applications.